/*
 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under both the BSD-style license (found in the
 * LICENSE file in the root directory of this source tree) and the GPLv2 (found
 * in the COPYING file in the root directory of this source tree).
 * You may select, at your option, one of the above-listed licenses.
 */

#include "zstd_lazy.h"

#include "zstd_compress_internal.h"

/*-*************************************
 *  Binary Tree search
 ***************************************/

static void ZSTD_updateDUBT(ZSTD_matchState_t* ms, const BYTE* ip, const BYTE* iend, U32 mls) {
    const ZSTD_compressionParameters* const cParams = &ms->cParams;
    U32* const hashTable = ms->hashTable;
    U32 const hashLog = cParams->hashLog;

    U32* const bt = ms->chainTable;
    U32 const btLog = cParams->chainLog - 1;
    U32 const btMask = (1 << btLog) - 1;

    const BYTE* const base = ms->window.base;
    U32 const target = (U32)(ip - base);
    U32 idx = ms->nextToUpdate;

    if (idx != target)
        DEBUGLOG(7, "ZSTD_updateDUBT, from %u to %u (dictLimit:%u)", idx, target, ms->window.dictLimit);
    assert(ip + 8 <= iend); /* condition for ZSTD_hashPtr */
    (void)iend;

    assert(idx >= ms->window.dictLimit); /* condition for valid base+idx */
    for (; idx < target; idx++) {
        size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls); /* assumption : ip + 8 <= iend */
        U32 const matchIndex = hashTable[h];

        U32* const nextCandidatePtr = bt + 2 * (idx & btMask);
        U32* const sortMarkPtr = nextCandidatePtr + 1;

        DEBUGLOG(8, "ZSTD_updateDUBT: insert %u", idx);
        hashTable[h] = idx;             /* Update Hash Table */
        *nextCandidatePtr = matchIndex; /* update BT like a chain */
        *sortMarkPtr = ZSTD_DUBT_UNSORTED_MARK;
    }
    ms->nextToUpdate = target;
}

/** ZSTD_insertDUBT1() :
 *  sort one already inserted but unsorted position
 *  assumption : current >= btlow == (current - btmask)
 *  doesn't fail */
static void ZSTD_insertDUBT1(ZSTD_matchState_t* ms,
                             U32 current,
                             const BYTE* inputEnd,
                             U32 nbCompares,
                             U32 btLow,
                             const ZSTD_dictMode_e dictMode) {
    const ZSTD_compressionParameters* const cParams = &ms->cParams;
    U32* const bt = ms->chainTable;
    U32 const btLog = cParams->chainLog - 1;
    U32 const btMask = (1 << btLog) - 1;
    size_t commonLengthSmaller = 0, commonLengthLarger = 0;
    const BYTE* const base = ms->window.base;
    const BYTE* const dictBase = ms->window.dictBase;
    const U32 dictLimit = ms->window.dictLimit;
    const BYTE* const ip = (current >= dictLimit) ? base + current : dictBase + current;
    const BYTE* const iend = (current >= dictLimit) ? inputEnd : dictBase + dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* match;
    U32* smallerPtr = bt + 2 * (current & btMask);
    U32* largerPtr = smallerPtr + 1;
    U32 matchIndex = *smallerPtr; /* this candidate is unsorted : next sorted candidate is reached through *smallerPtr,
                                     while *largerPtr contains previous unsorted candidate (which is already saved and
                                     can be overwritten) */
    U32 dummy32;                  /* to be nullified at the end */
    U32 const windowValid = ms->window.lowLimit;
    U32 const maxDistance = 1U << cParams->windowLog;
    U32 const windowLow = (current - windowValid > maxDistance) ? current - maxDistance : windowValid;

    DEBUGLOG(8, "ZSTD_insertDUBT1(%u) (dictLimit=%u, lowLimit=%u)", current, dictLimit, windowLow);
    assert(current >= btLow);
    assert(ip < iend); /* condition for ZSTD_count */

    while (nbCompares-- && (matchIndex > windowLow)) {
        U32* const nextPtr = bt + 2 * (matchIndex & btMask);
        size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
        assert(matchIndex < current);
        /* note : all candidates are now supposed sorted,
         * but it's still possible to have nextPtr[1] == ZSTD_DUBT_UNSORTED_MARK
         * when a real index has the same value as ZSTD_DUBT_UNSORTED_MARK */

        if ((dictMode != ZSTD_extDict) || (matchIndex + matchLength >= dictLimit) /* both in current segment*/
            || (current < dictLimit) /* both in extDict */) {
            const BYTE* const mBase =
                ((dictMode != ZSTD_extDict) || (matchIndex + matchLength >= dictLimit)) ? base : dictBase;
            assert((matchIndex + matchLength >= dictLimit) /* might be wrong if extDict is incorrectly set to 0 */
                   || (current < dictLimit));
            match = mBase + matchIndex;
            matchLength += ZSTD_count(ip + matchLength, match + matchLength, iend);
        } else {
            match = dictBase + matchIndex;
            matchLength += ZSTD_count_2segments(ip + matchLength, match + matchLength, iend, dictEnd, prefixStart);
            if (matchIndex + matchLength >= dictLimit)
                match = base + matchIndex; /* preparation for next read of match[matchLength] */
        }

        DEBUGLOG(8,
                 "ZSTD_insertDUBT1: comparing %u with %u : found %u common bytes ",
                 current,
                 matchIndex,
                 (U32)matchLength);

        if (ip + matchLength == iend) { /* equal : no way to know if inf or sup */
            break; /* drop , to guarantee consistency ; miss a bit of compression, but other solutions can corrupt tree
                    */
        }

        if (match[matchLength] < ip[matchLength]) { /* necessarily within buffer */
            /* match is smaller than current */
            *smallerPtr = matchIndex;          /* update smaller idx */
            commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
            if (matchIndex <= btLow) {
                smallerPtr = &dummy32;
                break;
            } /* beyond tree size, stop searching */
            DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is smaller : next => %u", matchIndex, btLow, nextPtr[1]);
            smallerPtr = nextPtr + 1; /* new "candidate" => larger than match, which was smaller than target */
            matchIndex = nextPtr[1];  /* new matchIndex, larger than previous and closer to current */
        } else {
            /* match is larger than current */
            *largerPtr = matchIndex;
            commonLengthLarger = matchLength;
            if (matchIndex <= btLow) {
                largerPtr = &dummy32;
                break;
            } /* beyond tree size, stop searching */
            DEBUGLOG(8, "ZSTD_insertDUBT1: %u (>btLow=%u) is larger => %u", matchIndex, btLow, nextPtr[0]);
            largerPtr = nextPtr;
            matchIndex = nextPtr[0];
        }
    }

    *smallerPtr = *largerPtr = 0;
}

static size_t ZSTD_DUBT_findBetterDictMatch(ZSTD_matchState_t* ms,
                                            const BYTE* const ip,
                                            const BYTE* const iend,
                                            size_t* offsetPtr,
                                            size_t bestLength,
                                            U32 nbCompares,
                                            U32 const mls,
                                            const ZSTD_dictMode_e dictMode) {
    const ZSTD_matchState_t* const dms = ms->dictMatchState;
    const ZSTD_compressionParameters* const dmsCParams = &dms->cParams;
    const U32* const dictHashTable = dms->hashTable;
    U32 const hashLog = dmsCParams->hashLog;
    size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
    U32 dictMatchIndex = dictHashTable[h];

    const BYTE* const base = ms->window.base;
    const BYTE* const prefixStart = base + ms->window.dictLimit;
    U32 const current = (U32)(ip - base);
    const BYTE* const dictBase = dms->window.base;
    const BYTE* const dictEnd = dms->window.nextSrc;
    U32 const dictHighLimit = (U32)(dms->window.nextSrc - dms->window.base);
    U32 const dictLowLimit = dms->window.lowLimit;
    U32 const dictIndexDelta = ms->window.lowLimit - dictHighLimit;

    U32* const dictBt = dms->chainTable;
    U32 const btLog = dmsCParams->chainLog - 1;
    U32 const btMask = (1 << btLog) - 1;
    U32 const btLow = (btMask >= dictHighLimit - dictLowLimit) ? dictLowLimit : dictHighLimit - btMask;

    size_t commonLengthSmaller = 0, commonLengthLarger = 0;

    (void)dictMode;
    assert(dictMode == ZSTD_dictMatchState);

    while (nbCompares-- && (dictMatchIndex > dictLowLimit)) {
        U32* const nextPtr = dictBt + 2 * (dictMatchIndex & btMask);
        size_t matchLength = MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
        const BYTE* match = dictBase + dictMatchIndex;
        matchLength += ZSTD_count_2segments(ip + matchLength, match + matchLength, iend, dictEnd, prefixStart);
        if (dictMatchIndex + matchLength >= dictHighLimit)
            match = base + dictMatchIndex + dictIndexDelta; /* to prepare for next usage of match[matchLength] */

        if (matchLength > bestLength) {
            U32 matchIndex = dictMatchIndex + dictIndexDelta;
            if ((4 * (int)(matchLength - bestLength))
                > (int)(ZSTD_highbit32(current - matchIndex + 1) - ZSTD_highbit32((U32)offsetPtr[0] + 1))) {
                DEBUGLOG(9,
                         "ZSTD_DUBT_findBetterDictMatch(%u) : found better match length %u -> %u and offsetCode %u -> "
                         "%u (dictMatchIndex %u, matchIndex %u)",
                         current,
                         (U32)bestLength,
                         (U32)matchLength,
                         (U32)*offsetPtr,
                         ZSTD_REP_MOVE + current - matchIndex,
                         dictMatchIndex,
                         matchIndex);
                bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
            }
            if (ip + matchLength == iend) { /* reached end of input : ip[matchLength] is not valid, no way to know if
                                               it's larger or smaller than match */
                break;                      /* drop, to guarantee consistency (miss a little bit of compression) */
            }
        }

        if (match[matchLength] < ip[matchLength]) {
            if (dictMatchIndex <= btLow) {
                break;
            }                                  /* beyond tree size, stop the search */
            commonLengthSmaller = matchLength; /* all smaller will now have at least this guaranteed common length */
            dictMatchIndex = nextPtr[1];       /* new matchIndex larger than previous (closer to current) */
        } else {
            /* match is larger than current */
            if (dictMatchIndex <= btLow) {
                break;
            } /* beyond tree size, stop the search */
            commonLengthLarger = matchLength;
            dictMatchIndex = nextPtr[0];
        }
    }

    if (bestLength >= MINMATCH) {
        U32 const mIndex = current - ((U32)*offsetPtr - ZSTD_REP_MOVE);
        (void)mIndex;
        DEBUGLOG(8,
                 "ZSTD_DUBT_findBetterDictMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
                 current,
                 (U32)bestLength,
                 (U32)*offsetPtr,
                 mIndex);
    }
    return bestLength;
}

static size_t ZSTD_DUBT_findBestMatch(ZSTD_matchState_t* ms,
                                      const BYTE* const ip,
                                      const BYTE* const iend,
                                      size_t* offsetPtr,
                                      U32 const mls,
                                      const ZSTD_dictMode_e dictMode) {
    const ZSTD_compressionParameters* const cParams = &ms->cParams;
    U32* const hashTable = ms->hashTable;
    U32 const hashLog = cParams->hashLog;
    size_t const h = ZSTD_hashPtr(ip, hashLog, mls);
    U32 matchIndex = hashTable[h];

    const BYTE* const base = ms->window.base;
    U32 const current = (U32)(ip - base);
    U32 const windowLow = ZSTD_getLowestMatchIndex(ms, current, cParams->windowLog);

    U32* const bt = ms->chainTable;
    U32 const btLog = cParams->chainLog - 1;
    U32 const btMask = (1 << btLog) - 1;
    U32 const btLow = (btMask >= current) ? 0 : current - btMask;
    U32 const unsortLimit = MAX(btLow, windowLow);

    U32* nextCandidate = bt + 2 * (matchIndex & btMask);
    U32* unsortedMark = bt + 2 * (matchIndex & btMask) + 1;
    U32 nbCompares = 1U << cParams->searchLog;
    U32 nbCandidates = nbCompares;
    U32 previousCandidate = 0;

    DEBUGLOG(7, "ZSTD_DUBT_findBestMatch (%u) ", current);
    assert(ip <= iend - 8); /* required for h calculation */

    /* reach end of unsorted candidates list */
    while ((matchIndex > unsortLimit) && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK) && (nbCandidates > 1)) {
        DEBUGLOG(8, "ZSTD_DUBT_findBestMatch: candidate %u is unsorted", matchIndex);
        *unsortedMark =
            previousCandidate; /* the unsortedMark becomes a reversed chain, to move up back to original position */
        previousCandidate = matchIndex;
        matchIndex = *nextCandidate;
        nextCandidate = bt + 2 * (matchIndex & btMask);
        unsortedMark = bt + 2 * (matchIndex & btMask) + 1;
        nbCandidates--;
    }

    /* nullify last candidate if it's still unsorted
     * simplification, detrimental to compression ratio, beneficial for speed */
    if ((matchIndex > unsortLimit) && (*unsortedMark == ZSTD_DUBT_UNSORTED_MARK)) {
        DEBUGLOG(7, "ZSTD_DUBT_findBestMatch: nullify last unsorted candidate %u", matchIndex);
        *nextCandidate = *unsortedMark = 0;
    }

    /* batch sort stacked candidates */
    matchIndex = previousCandidate;
    while (matchIndex) { /* will end on matchIndex == 0 */
        U32* const nextCandidateIdxPtr = bt + 2 * (matchIndex & btMask) + 1;
        U32 const nextCandidateIdx = *nextCandidateIdxPtr;
        ZSTD_insertDUBT1(ms, matchIndex, iend, nbCandidates, unsortLimit, dictMode);
        matchIndex = nextCandidateIdx;
        nbCandidates++;
    }

    /* find longest match */
    {
        size_t commonLengthSmaller = 0, commonLengthLarger = 0;
        const BYTE* const dictBase = ms->window.dictBase;
        const U32 dictLimit = ms->window.dictLimit;
        const BYTE* const dictEnd = dictBase + dictLimit;
        const BYTE* const prefixStart = base + dictLimit;
        U32* smallerPtr = bt + 2 * (current & btMask);
        U32* largerPtr = bt + 2 * (current & btMask) + 1;
        U32 matchEndIdx = current + 8 + 1;
        U32 dummy32; /* to be nullified at the end */
        size_t bestLength = 0;

        matchIndex = hashTable[h];
        hashTable[h] = current; /* Update Hash Table */

        while (nbCompares-- && (matchIndex > windowLow)) {
            U32* const nextPtr = bt + 2 * (matchIndex & btMask);
            size_t matchLength =
                MIN(commonLengthSmaller, commonLengthLarger); /* guaranteed minimum nb of common bytes */
            const BYTE* match;

            if ((dictMode != ZSTD_extDict) || (matchIndex + matchLength >= dictLimit)) {
                match = base + matchIndex;
                matchLength += ZSTD_count(ip + matchLength, match + matchLength, iend);
            } else {
                match = dictBase + matchIndex;
                matchLength += ZSTD_count_2segments(ip + matchLength, match + matchLength, iend, dictEnd, prefixStart);
                if (matchIndex + matchLength >= dictLimit)
                    match = base + matchIndex; /* to prepare for next usage of match[matchLength] */
            }

            if (matchLength > bestLength) {
                if (matchLength > matchEndIdx - matchIndex)
                    matchEndIdx = matchIndex + (U32)matchLength;
                if ((4 * (int)(matchLength - bestLength))
                    > (int)(ZSTD_highbit32(current - matchIndex + 1) - ZSTD_highbit32((U32)offsetPtr[0] + 1)))
                    bestLength = matchLength, *offsetPtr = ZSTD_REP_MOVE + current - matchIndex;
                if (ip + matchLength == iend) { /* equal : no way to know if inf or sup */
                    if (dictMode == ZSTD_dictMatchState) {
                        nbCompares = 0; /* in addition to avoiding checking any
                                         * further in this loop, make sure we
                                         * skip checking in the dictionary. */
                    }
                    break; /* drop, to guarantee consistency (miss a little bit of compression) */
                }
            }

            if (match[matchLength] < ip[matchLength]) {
                /* match is smaller than current */
                *smallerPtr = matchIndex; /* update smaller idx */
                commonLengthSmaller =
                    matchLength; /* all smaller will now have at least this guaranteed common length */
                if (matchIndex <= btLow) {
                    smallerPtr = &dummy32;
                    break;
                }                         /* beyond tree size, stop the search */
                smallerPtr = nextPtr + 1; /* new "smaller" => larger of match */
                matchIndex = nextPtr[1];  /* new matchIndex larger than previous (closer to current) */
            } else {
                /* match is larger than current */
                *largerPtr = matchIndex;
                commonLengthLarger = matchLength;
                if (matchIndex <= btLow) {
                    largerPtr = &dummy32;
                    break;
                } /* beyond tree size, stop the search */
                largerPtr = nextPtr;
                matchIndex = nextPtr[0];
            }
        }

        *smallerPtr = *largerPtr = 0;

        if (dictMode == ZSTD_dictMatchState && nbCompares) {
            bestLength = ZSTD_DUBT_findBetterDictMatch(ms, ip, iend, offsetPtr, bestLength, nbCompares, mls, dictMode);
        }

        assert(matchEndIdx > current + 8);  /* ensure nextToUpdate is increased */
        ms->nextToUpdate = matchEndIdx - 8; /* skip repetitive patterns */
        if (bestLength >= MINMATCH) {
            U32 const mIndex = current - ((U32)*offsetPtr - ZSTD_REP_MOVE);
            (void)mIndex;
            DEBUGLOG(8,
                     "ZSTD_DUBT_findBestMatch(%u) : found match of length %u and offsetCode %u (pos %u)",
                     current,
                     (U32)bestLength,
                     (U32)*offsetPtr,
                     mIndex);
        }
        return bestLength;
    }
}

/** ZSTD_BtFindBestMatch() : Tree updater, providing best match */
FORCE_INLINE_TEMPLATE size_t ZSTD_BtFindBestMatch(ZSTD_matchState_t* ms,
                                                  const BYTE* const ip,
                                                  const BYTE* const iLimit,
                                                  size_t* offsetPtr,
                                                  const U32 mls /* template */,
                                                  const ZSTD_dictMode_e dictMode) {
    DEBUGLOG(7, "ZSTD_BtFindBestMatch");
    if (ip < ms->window.base + ms->nextToUpdate)
        return 0; /* skipped area */
    ZSTD_updateDUBT(ms, ip, iLimit, mls);
    return ZSTD_DUBT_findBestMatch(ms, ip, iLimit, offsetPtr, mls, dictMode);
}

static size_t ZSTD_BtFindBestMatch_selectMLS(ZSTD_matchState_t* ms,
                                             const BYTE* ip,
                                             const BYTE* const iLimit,
                                             size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_noDict);
        case 5:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_noDict);
        case 7:
        case 6:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_noDict);
    }
}

static size_t ZSTD_BtFindBestMatch_dictMatchState_selectMLS(ZSTD_matchState_t* ms,
                                                            const BYTE* ip,
                                                            const BYTE* const iLimit,
                                                            size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_dictMatchState);
        case 5:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_dictMatchState);
        case 7:
        case 6:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_dictMatchState);
    }
}

static size_t ZSTD_BtFindBestMatch_extDict_selectMLS(ZSTD_matchState_t* ms,
                                                     const BYTE* ip,
                                                     const BYTE* const iLimit,
                                                     size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 4, ZSTD_extDict);
        case 5:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 5, ZSTD_extDict);
        case 7:
        case 6:
            return ZSTD_BtFindBestMatch(ms, ip, iLimit, offsetPtr, 6, ZSTD_extDict);
    }
}

/* *********************************
 *  Hash Chain
 ***********************************/
#define NEXT_IN_CHAIN(d, mask) chainTable[(d) & (mask)]

/* Update chains up to ip (excluded)
   Assumption : always within prefix (i.e. not within extDict) */
static U32 ZSTD_insertAndFindFirstIndex_internal(ZSTD_matchState_t* ms,
                                                 const ZSTD_compressionParameters* const cParams,
                                                 const BYTE* ip,
                                                 U32 const mls) {
    U32* const hashTable = ms->hashTable;
    const U32 hashLog = cParams->hashLog;
    U32* const chainTable = ms->chainTable;
    const U32 chainMask = (1 << cParams->chainLog) - 1;
    const BYTE* const base = ms->window.base;
    const U32 target = (U32)(ip - base);
    U32 idx = ms->nextToUpdate;

    while (idx < target) { /* catch up */
        size_t const h = ZSTD_hashPtr(base + idx, hashLog, mls);
        NEXT_IN_CHAIN(idx, chainMask) = hashTable[h];
        hashTable[h] = idx;
        idx++;
    }

    ms->nextToUpdate = target;
    return hashTable[ZSTD_hashPtr(ip, hashLog, mls)];
}

U32 ZSTD_insertAndFindFirstIndex(ZSTD_matchState_t* ms, const BYTE* ip) {
    const ZSTD_compressionParameters* const cParams = &ms->cParams;
    return ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, ms->cParams.minMatch);
}

/* inlining is important to hardwire a hot branch (template emulation) */
FORCE_INLINE_TEMPLATE
size_t ZSTD_HcFindBestMatch_generic(ZSTD_matchState_t* ms,
                                    const BYTE* const ip,
                                    const BYTE* const iLimit,
                                    size_t* offsetPtr,
                                    const U32 mls,
                                    const ZSTD_dictMode_e dictMode) {
    const ZSTD_compressionParameters* const cParams = &ms->cParams;
    U32* const chainTable = ms->chainTable;
    const U32 chainSize = (1 << cParams->chainLog);
    const U32 chainMask = chainSize - 1;
    const BYTE* const base = ms->window.base;
    const BYTE* const dictBase = ms->window.dictBase;
    const U32 dictLimit = ms->window.dictLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const U32 current = (U32)(ip - base);
    const U32 maxDistance = 1U << cParams->windowLog;
    const U32 lowestValid = ms->window.lowLimit;
    const U32 withinMaxDistance = (current - lowestValid > maxDistance) ? current - maxDistance : lowestValid;
    const U32 isDictionary = (ms->loadedDictEnd != 0);
    const U32 lowLimit = isDictionary ? lowestValid : withinMaxDistance;
    const U32 minChain = current > chainSize ? current - chainSize : 0;
    U32 nbAttempts = 1U << cParams->searchLog;
    size_t ml = 4 - 1;

    /* HC4 match finder */
    U32 matchIndex = ZSTD_insertAndFindFirstIndex_internal(ms, cParams, ip, mls);

    for (; (matchIndex > lowLimit) & (nbAttempts > 0); nbAttempts--) {
        size_t currentMl = 0;
        if ((dictMode != ZSTD_extDict) || matchIndex >= dictLimit) {
            const BYTE* const match = base + matchIndex;
            assert(matchIndex >= dictLimit); /* ensures this is true if dictMode != ZSTD_extDict */
            if (match[ml] == ip[ml])         /* potentially better */
                currentMl = ZSTD_count(ip, match, iLimit);
        } else {
            const BYTE* const match = dictBase + matchIndex;
            assert(match + 4 <= dictEnd);
            if (MEM_read32(match)
                == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
                currentMl = ZSTD_count_2segments(ip + 4, match + 4, iLimit, dictEnd, prefixStart) + 4;
        }

        /* save best solution */
        if (currentMl > ml) {
            ml = currentMl;
            *offsetPtr = current - matchIndex + ZSTD_REP_MOVE;
            if (ip + currentMl == iLimit)
                break; /* best possible, avoids read overflow on next attempt */
        }

        if (matchIndex <= minChain)
            break;
        matchIndex = NEXT_IN_CHAIN(matchIndex, chainMask);
    }

    if (dictMode == ZSTD_dictMatchState) {
        const ZSTD_matchState_t* const dms = ms->dictMatchState;
        const U32* const dmsChainTable = dms->chainTable;
        const U32 dmsChainSize = (1 << dms->cParams.chainLog);
        const U32 dmsChainMask = dmsChainSize - 1;
        const U32 dmsLowestIndex = dms->window.dictLimit;
        const BYTE* const dmsBase = dms->window.base;
        const BYTE* const dmsEnd = dms->window.nextSrc;
        const U32 dmsSize = (U32)(dmsEnd - dmsBase);
        const U32 dmsIndexDelta = dictLimit - dmsSize;
        const U32 dmsMinChain = dmsSize > dmsChainSize ? dmsSize - dmsChainSize : 0;

        matchIndex = dms->hashTable[ZSTD_hashPtr(ip, dms->cParams.hashLog, mls)];

        for (; (matchIndex > dmsLowestIndex) & (nbAttempts > 0); nbAttempts--) {
            size_t currentMl = 0;
            const BYTE* const match = dmsBase + matchIndex;
            assert(match + 4 <= dmsEnd);
            if (MEM_read32(match)
                == MEM_read32(ip)) /* assumption : matchIndex <= dictLimit-4 (by table construction) */
                currentMl = ZSTD_count_2segments(ip + 4, match + 4, iLimit, dmsEnd, prefixStart) + 4;

            /* save best solution */
            if (currentMl > ml) {
                ml = currentMl;
                *offsetPtr = current - (matchIndex + dmsIndexDelta) + ZSTD_REP_MOVE;
                if (ip + currentMl == iLimit)
                    break; /* best possible, avoids read overflow on next attempt */
            }

            if (matchIndex <= dmsMinChain)
                break;
            matchIndex = dmsChainTable[matchIndex & dmsChainMask];
        }
    }

    return ml;
}

FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_selectMLS(ZSTD_matchState_t* ms,
                                                            const BYTE* ip,
                                                            const BYTE* const iLimit,
                                                            size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_noDict);
        case 5:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_noDict);
        case 7:
        case 6:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_noDict);
    }
}

static size_t ZSTD_HcFindBestMatch_dictMatchState_selectMLS(ZSTD_matchState_t* ms,
                                                            const BYTE* ip,
                                                            const BYTE* const iLimit,
                                                            size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_dictMatchState);
        case 5:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_dictMatchState);
        case 7:
        case 6:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_dictMatchState);
    }
}

FORCE_INLINE_TEMPLATE size_t ZSTD_HcFindBestMatch_extDict_selectMLS(ZSTD_matchState_t* ms,
                                                                    const BYTE* ip,
                                                                    const BYTE* const iLimit,
                                                                    size_t* offsetPtr) {
    switch (ms->cParams.minMatch) {
        default: /* includes case 3 */
        case 4:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 4, ZSTD_extDict);
        case 5:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 5, ZSTD_extDict);
        case 7:
        case 6:
            return ZSTD_HcFindBestMatch_generic(ms, ip, iLimit, offsetPtr, 6, ZSTD_extDict);
    }
}

/* *******************************
 *  Common parser - lazy strategy
 *********************************/
typedef enum { search_hashChain, search_binaryTree } searchMethod_e;

FORCE_INLINE_TEMPLATE size_t ZSTD_compressBlock_lazy_generic(ZSTD_matchState_t* ms,
                                                             seqStore_t* seqStore,
                                                             U32 rep[ZSTD_REP_NUM],
                                                             const void* src,
                                                             size_t srcSize,
                                                             const searchMethod_e searchMethod,
                                                             const U32 depth,
                                                             ZSTD_dictMode_e const dictMode) {
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    const BYTE* const base = ms->window.base;
    const U32 prefixLowestIndex = ms->window.dictLimit;
    const BYTE* const prefixLowest = base + prefixLowestIndex;

    typedef size_t (*searchMax_f)(ZSTD_matchState_t * ms, const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
    searchMax_f const searchMax =
        dictMode == ZSTD_dictMatchState
            ? (searchMethod == search_binaryTree ? ZSTD_BtFindBestMatch_dictMatchState_selectMLS
                                                 : ZSTD_HcFindBestMatch_dictMatchState_selectMLS)
            : (searchMethod == search_binaryTree ? ZSTD_BtFindBestMatch_selectMLS : ZSTD_HcFindBestMatch_selectMLS);
    U32 offset_1 = rep[0], offset_2 = rep[1], savedOffset = 0;

    const ZSTD_matchState_t* const dms = ms->dictMatchState;
    const U32 dictLowestIndex = dictMode == ZSTD_dictMatchState ? dms->window.dictLimit : 0;
    const BYTE* const dictBase = dictMode == ZSTD_dictMatchState ? dms->window.base : NULL;
    const BYTE* const dictLowest = dictMode == ZSTD_dictMatchState ? dictBase + dictLowestIndex : NULL;
    const BYTE* const dictEnd = dictMode == ZSTD_dictMatchState ? dms->window.nextSrc : NULL;
    const U32 dictIndexDelta = dictMode == ZSTD_dictMatchState ? prefixLowestIndex - (U32)(dictEnd - dictBase) : 0;
    const U32 dictAndPrefixLength = (U32)(ip - prefixLowest + dictEnd - dictLowest);

    /* init */
    ip += (dictAndPrefixLength == 0);
    if (dictMode == ZSTD_noDict) {
        U32 const maxRep = (U32)(ip - prefixLowest);
        if (offset_2 > maxRep)
            savedOffset = offset_2, offset_2 = 0;
        if (offset_1 > maxRep)
            savedOffset = offset_1, offset_1 = 0;
    }
    if (dictMode == ZSTD_dictMatchState) {
        /* dictMatchState repCode checks don't currently handle repCode == 0
         * disabling. */
        assert(offset_1 <= dictAndPrefixLength);
        assert(offset_2 <= dictAndPrefixLength);
    }

    /* Match Loop */
    while (ip < ilimit) {
        size_t matchLength = 0;
        size_t offset = 0;
        const BYTE* start = ip + 1;

        /* check repCode */
        if (dictMode == ZSTD_dictMatchState) {
            const U32 repIndex = (U32)(ip - base) + 1 - offset_1;
            const BYTE* repMatch = (dictMode == ZSTD_dictMatchState && repIndex < prefixLowestIndex)
                                       ? dictBase + (repIndex - dictIndexDelta)
                                       : base + repIndex;
            if (((U32)((prefixLowestIndex - 1) - repIndex) >= 3 /* intentional underflow */)
                && (MEM_read32(repMatch) == MEM_read32(ip + 1))) {
                const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
                matchLength = ZSTD_count_2segments(ip + 1 + 4, repMatch + 4, iend, repMatchEnd, prefixLowest) + 4;
                if (depth == 0)
                    goto _storeSequence;
            }
        }
        if (dictMode == ZSTD_noDict && ((offset_1 > 0) & (MEM_read32(ip + 1 - offset_1) == MEM_read32(ip + 1)))) {
            matchLength = ZSTD_count(ip + 1 + 4, ip + 1 + 4 - offset_1, iend) + 4;
            if (depth == 0)
                goto _storeSequence;
        }

        /* first search (depth 0) */
        {
            size_t offsetFound = 999999999;
            size_t const ml2 = searchMax(ms, ip, iend, &offsetFound);
            if (ml2 > matchLength)
                matchLength = ml2, start = ip, offset = offsetFound;
        }

        if (matchLength < 4) {
            ip += ((ip - anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
            continue;
        }

        /* let's try to find a better solution */
        if (depth >= 1)
            while (ip < ilimit) {
                ip++;
                if ((dictMode == ZSTD_noDict) && (offset)
                    && ((offset_1 > 0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
                    size_t const mlRep = ZSTD_count(ip + 4, ip + 4 - offset_1, iend) + 4;
                    int const gain2 = (int)(mlRep * 3);
                    int const gain1 = (int)(matchLength * 3 - ZSTD_highbit32((U32)offset + 1) + 1);
                    if ((mlRep >= 4) && (gain2 > gain1))
                        matchLength = mlRep, offset = 0, start = ip;
                }
                if (dictMode == ZSTD_dictMatchState) {
                    const U32 repIndex = (U32)(ip - base) - offset_1;
                    const BYTE* repMatch =
                        repIndex < prefixLowestIndex ? dictBase + (repIndex - dictIndexDelta) : base + repIndex;
                    if (((U32)((prefixLowestIndex - 1) - repIndex) >= 3 /* intentional underflow */)
                        && (MEM_read32(repMatch) == MEM_read32(ip))) {
                        const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
                        size_t const mlRep =
                            ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repMatchEnd, prefixLowest) + 4;
                        int const gain2 = (int)(mlRep * 3);
                        int const gain1 = (int)(matchLength * 3 - ZSTD_highbit32((U32)offset + 1) + 1);
                        if ((mlRep >= 4) && (gain2 > gain1))
                            matchLength = mlRep, offset = 0, start = ip;
                    }
                }
                {
                    size_t offset2 = 999999999;
                    size_t const ml2 = searchMax(ms, ip, iend, &offset2);
                    int const gain2 = (int)(ml2 * 4 - ZSTD_highbit32((U32)offset2 + 1)); /* raw approx */
                    int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 4);
                    if ((ml2 >= 4) && (gain2 > gain1)) {
                        matchLength = ml2, offset = offset2, start = ip;
                        continue; /* search a better one */
                    }
                }

                /* let's find an even better one */
                if ((depth == 2) && (ip < ilimit)) {
                    ip++;
                    if ((dictMode == ZSTD_noDict) && (offset)
                        && ((offset_1 > 0) & (MEM_read32(ip) == MEM_read32(ip - offset_1)))) {
                        size_t const mlRep = ZSTD_count(ip + 4, ip + 4 - offset_1, iend) + 4;
                        int const gain2 = (int)(mlRep * 4);
                        int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 1);
                        if ((mlRep >= 4) && (gain2 > gain1))
                            matchLength = mlRep, offset = 0, start = ip;
                    }
                    if (dictMode == ZSTD_dictMatchState) {
                        const U32 repIndex = (U32)(ip - base) - offset_1;
                        const BYTE* repMatch =
                            repIndex < prefixLowestIndex ? dictBase + (repIndex - dictIndexDelta) : base + repIndex;
                        if (((U32)((prefixLowestIndex - 1) - repIndex) >= 3 /* intentional underflow */)
                            && (MEM_read32(repMatch) == MEM_read32(ip))) {
                            const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;
                            size_t const mlRep =
                                ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repMatchEnd, prefixLowest) + 4;
                            int const gain2 = (int)(mlRep * 4);
                            int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 1);
                            if ((mlRep >= 4) && (gain2 > gain1))
                                matchLength = mlRep, offset = 0, start = ip;
                        }
                    }
                    {
                        size_t offset2 = 999999999;
                        size_t const ml2 = searchMax(ms, ip, iend, &offset2);
                        int const gain2 = (int)(ml2 * 4 - ZSTD_highbit32((U32)offset2 + 1)); /* raw approx */
                        int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 7);
                        if ((ml2 >= 4) && (gain2 > gain1)) {
                            matchLength = ml2, offset = offset2, start = ip;
                            continue;
                        }
                    }
                }
                break; /* nothing found : store previous solution */
            }

        /* NOTE:
         * start[-offset+ZSTD_REP_MOVE-1] is undefined behavior.
         * (-offset+ZSTD_REP_MOVE-1) is unsigned, and is added to start, which
         * overflows the pointer, which is undefined behavior.
         */
        /* catch up */
        if (offset) {
            if (dictMode == ZSTD_noDict) {
                while (
                    ((start > anchor) & (start - (offset - ZSTD_REP_MOVE) > prefixLowest))
                    && (start[-1] == (start - (offset - ZSTD_REP_MOVE))[-1])) /* only search for offset within prefix */
                {
                    start--;
                    matchLength++;
                }
            }
            if (dictMode == ZSTD_dictMatchState) {
                U32 const matchIndex = (U32)((start - base) - (offset - ZSTD_REP_MOVE));
                const BYTE* match =
                    (matchIndex < prefixLowestIndex) ? dictBase + matchIndex - dictIndexDelta : base + matchIndex;
                const BYTE* const mStart = (matchIndex < prefixLowestIndex) ? dictLowest : prefixLowest;
                while ((start > anchor) && (match > mStart) && (start[-1] == match[-1])) {
                    start--;
                    match--;
                    matchLength++;
                } /* catch up */
            }
            offset_2 = offset_1;
            offset_1 = (U32)(offset - ZSTD_REP_MOVE);
        }
        /* store sequence */
    _storeSequence : {
        size_t const litLength = start - anchor;
        ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength - MINMATCH);
        anchor = ip = start + matchLength;
    }

        /* check immediate repcode */
        if (dictMode == ZSTD_dictMatchState) {
            while (ip <= ilimit) {
                U32 const current2 = (U32)(ip - base);
                U32 const repIndex = current2 - offset_2;
                const BYTE* repMatch = dictMode == ZSTD_dictMatchState && repIndex < prefixLowestIndex
                                           ? dictBase - dictIndexDelta + repIndex
                                           : base + repIndex;
                if (((U32)((prefixLowestIndex - 1) - (U32)repIndex) >= 3 /* intentional overflow */)
                    && (MEM_read32(repMatch) == MEM_read32(ip))) {
                    const BYTE* const repEnd2 = repIndex < prefixLowestIndex ? dictEnd : iend;
                    matchLength = ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repEnd2, prefixLowest) + 4;
                    offset = offset_2;
                    offset_2 = offset_1;
                    offset_1 = (U32)offset; /* swap offset_2 <=> offset_1 */
                    ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength - MINMATCH);
                    ip += matchLength;
                    anchor = ip;
                    continue;
                }
                break;
            }
        }

        if (dictMode == ZSTD_noDict) {
            while (((ip <= ilimit) & (offset_2 > 0)) && (MEM_read32(ip) == MEM_read32(ip - offset_2))) {
                /* store sequence */
                matchLength = ZSTD_count(ip + 4, ip + 4 - offset_2, iend) + 4;
                offset = offset_2;
                offset_2 = offset_1;
                offset_1 = (U32)offset; /* swap repcodes */
                ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength - MINMATCH);
                ip += matchLength;
                anchor = ip;
                continue; /* faster when present ... (?) */
            }
        }
    }

    /* Save reps for next block */
    rep[0] = offset_1 ? offset_1 : savedOffset;
    rep[1] = offset_2 ? offset_2 : savedOffset;

    /* Return the last literals size */
    return (size_t)(iend - anchor);
}

size_t ZSTD_compressBlock_btlazy2(ZSTD_matchState_t* ms,
                                  seqStore_t* seqStore,
                                  U32 rep[ZSTD_REP_NUM],
                                  void const* src,
                                  size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_noDict);
}

size_t ZSTD_compressBlock_lazy2(ZSTD_matchState_t* ms,
                                seqStore_t* seqStore,
                                U32 rep[ZSTD_REP_NUM],
                                void const* src,
                                size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_noDict);
}

size_t ZSTD_compressBlock_lazy(ZSTD_matchState_t* ms,
                               seqStore_t* seqStore,
                               U32 rep[ZSTD_REP_NUM],
                               void const* src,
                               size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_noDict);
}

size_t ZSTD_compressBlock_greedy(ZSTD_matchState_t* ms,
                                 seqStore_t* seqStore,
                                 U32 rep[ZSTD_REP_NUM],
                                 void const* src,
                                 size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_noDict);
}

size_t ZSTD_compressBlock_btlazy2_dictMatchState(ZSTD_matchState_t* ms,
                                                 seqStore_t* seqStore,
                                                 U32 rep[ZSTD_REP_NUM],
                                                 void const* src,
                                                 size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2, ZSTD_dictMatchState);
}

size_t ZSTD_compressBlock_lazy2_dictMatchState(ZSTD_matchState_t* ms,
                                               seqStore_t* seqStore,
                                               U32 rep[ZSTD_REP_NUM],
                                               void const* src,
                                               size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2, ZSTD_dictMatchState);
}

size_t ZSTD_compressBlock_lazy_dictMatchState(ZSTD_matchState_t* ms,
                                              seqStore_t* seqStore,
                                              U32 rep[ZSTD_REP_NUM],
                                              void const* src,
                                              size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1, ZSTD_dictMatchState);
}

size_t ZSTD_compressBlock_greedy_dictMatchState(ZSTD_matchState_t* ms,
                                                seqStore_t* seqStore,
                                                U32 rep[ZSTD_REP_NUM],
                                                void const* src,
                                                size_t srcSize) {
    return ZSTD_compressBlock_lazy_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0, ZSTD_dictMatchState);
}

FORCE_INLINE_TEMPLATE
size_t ZSTD_compressBlock_lazy_extDict_generic(ZSTD_matchState_t* ms,
                                               seqStore_t* seqStore,
                                               U32 rep[ZSTD_REP_NUM],
                                               const void* src,
                                               size_t srcSize,
                                               const searchMethod_e searchMethod,
                                               const U32 depth) {
    const BYTE* const istart = (const BYTE*)src;
    const BYTE* ip = istart;
    const BYTE* anchor = istart;
    const BYTE* const iend = istart + srcSize;
    const BYTE* const ilimit = iend - 8;
    const BYTE* const base = ms->window.base;
    const U32 dictLimit = ms->window.dictLimit;
    const U32 lowestIndex = ms->window.lowLimit;
    const BYTE* const prefixStart = base + dictLimit;
    const BYTE* const dictBase = ms->window.dictBase;
    const BYTE* const dictEnd = dictBase + dictLimit;
    const BYTE* const dictStart = dictBase + lowestIndex;

    typedef size_t (*searchMax_f)(ZSTD_matchState_t * ms, const BYTE* ip, const BYTE* iLimit, size_t* offsetPtr);
    searchMax_f searchMax = searchMethod == search_binaryTree ? ZSTD_BtFindBestMatch_extDict_selectMLS
                                                              : ZSTD_HcFindBestMatch_extDict_selectMLS;

    U32 offset_1 = rep[0], offset_2 = rep[1];

    /* init */
    ip += (ip == prefixStart);

    /* Match Loop */
    while (ip < ilimit) {
        size_t matchLength = 0;
        size_t offset = 0;
        const BYTE* start = ip + 1;
        U32 current = (U32)(ip - base);

        /* check repCode */
        {
            const U32 repIndex = (U32)(current + 1 - offset_1);
            const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
            const BYTE* const repMatch = repBase + repIndex;
            if (((U32)((dictLimit - 1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
                if (MEM_read32(ip + 1) == MEM_read32(repMatch)) {
                    /* repcode detected we should take it */
                    const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                    matchLength = ZSTD_count_2segments(ip + 1 + 4, repMatch + 4, iend, repEnd, prefixStart) + 4;
                    if (depth == 0)
                        goto _storeSequence;
                }
        }

        /* first search (depth 0) */
        {
            size_t offsetFound = 999999999;
            size_t const ml2 = searchMax(ms, ip, iend, &offsetFound);
            if (ml2 > matchLength)
                matchLength = ml2, start = ip, offset = offsetFound;
        }

        if (matchLength < 4) {
            ip += ((ip - anchor) >> kSearchStrength) + 1; /* jump faster over incompressible sections */
            continue;
        }

        /* let's try to find a better solution */
        if (depth >= 1)
            while (ip < ilimit) {
                ip++;
                current++;
                /* check repCode */
                if (offset) {
                    const U32 repIndex = (U32)(current - offset_1);
                    const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                    const BYTE* const repMatch = repBase + repIndex;
                    if (((U32)((dictLimit - 1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
                        if (MEM_read32(ip) == MEM_read32(repMatch)) {
                            /* repcode detected */
                            const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                            size_t const repLength =
                                ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repEnd, prefixStart) + 4;
                            int const gain2 = (int)(repLength * 3);
                            int const gain1 = (int)(matchLength * 3 - ZSTD_highbit32((U32)offset + 1) + 1);
                            if ((repLength >= 4) && (gain2 > gain1))
                                matchLength = repLength, offset = 0, start = ip;
                        }
                }

                /* search match, depth 1 */
                {
                    size_t offset2 = 999999999;
                    size_t const ml2 = searchMax(ms, ip, iend, &offset2);
                    int const gain2 = (int)(ml2 * 4 - ZSTD_highbit32((U32)offset2 + 1)); /* raw approx */
                    int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 4);
                    if ((ml2 >= 4) && (gain2 > gain1)) {
                        matchLength = ml2, offset = offset2, start = ip;
                        continue; /* search a better one */
                    }
                }

                /* let's find an even better one */
                if ((depth == 2) && (ip < ilimit)) {
                    ip++;
                    current++;
                    /* check repCode */
                    if (offset) {
                        const U32 repIndex = (U32)(current - offset_1);
                        const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
                        const BYTE* const repMatch = repBase + repIndex;
                        if (((U32)((dictLimit - 1) - repIndex) >= 3)
                            & (repIndex > lowestIndex)) /* intentional overflow */
                            if (MEM_read32(ip) == MEM_read32(repMatch)) {
                                /* repcode detected */
                                const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                                size_t const repLength =
                                    ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repEnd, prefixStart) + 4;
                                int const gain2 = (int)(repLength * 4);
                                int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 1);
                                if ((repLength >= 4) && (gain2 > gain1))
                                    matchLength = repLength, offset = 0, start = ip;
                            }
                    }

                    /* search match, depth 2 */
                    {
                        size_t offset2 = 999999999;
                        size_t const ml2 = searchMax(ms, ip, iend, &offset2);
                        int const gain2 = (int)(ml2 * 4 - ZSTD_highbit32((U32)offset2 + 1)); /* raw approx */
                        int const gain1 = (int)(matchLength * 4 - ZSTD_highbit32((U32)offset + 1) + 7);
                        if ((ml2 >= 4) && (gain2 > gain1)) {
                            matchLength = ml2, offset = offset2, start = ip;
                            continue;
                        }
                    }
                }
                break; /* nothing found : store previous solution */
            }

        /* catch up */
        if (offset) {
            U32 const matchIndex = (U32)((start - base) - (offset - ZSTD_REP_MOVE));
            const BYTE* match = (matchIndex < dictLimit) ? dictBase + matchIndex : base + matchIndex;
            const BYTE* const mStart = (matchIndex < dictLimit) ? dictStart : prefixStart;
            while ((start > anchor) && (match > mStart) && (start[-1] == match[-1])) {
                start--;
                match--;
                matchLength++;
            } /* catch up */
            offset_2 = offset_1;
            offset_1 = (U32)(offset - ZSTD_REP_MOVE);
        }

        /* store sequence */
    _storeSequence : {
        size_t const litLength = start - anchor;
        ZSTD_storeSeq(seqStore, litLength, anchor, iend, (U32)offset, matchLength - MINMATCH);
        anchor = ip = start + matchLength;
    }

        /* check immediate repcode */
        while (ip <= ilimit) {
            const U32 repIndex = (U32)((ip - base) - offset_2);
            const BYTE* const repBase = repIndex < dictLimit ? dictBase : base;
            const BYTE* const repMatch = repBase + repIndex;
            if (((U32)((dictLimit - 1) - repIndex) >= 3) & (repIndex > lowestIndex)) /* intentional overflow */
                if (MEM_read32(ip) == MEM_read32(repMatch)) {
                    /* repcode detected we should take it */
                    const BYTE* const repEnd = repIndex < dictLimit ? dictEnd : iend;
                    matchLength = ZSTD_count_2segments(ip + 4, repMatch + 4, iend, repEnd, prefixStart) + 4;
                    offset = offset_2;
                    offset_2 = offset_1;
                    offset_1 = (U32)offset; /* swap offset history */
                    ZSTD_storeSeq(seqStore, 0, anchor, iend, 0, matchLength - MINMATCH);
                    ip += matchLength;
                    anchor = ip;
                    continue; /* faster when present ... (?) */
                }
            break;
        }
    }

    /* Save reps for next block */
    rep[0] = offset_1;
    rep[1] = offset_2;

    /* Return the last literals size */
    return (size_t)(iend - anchor);
}

size_t ZSTD_compressBlock_greedy_extDict(ZSTD_matchState_t* ms,
                                         seqStore_t* seqStore,
                                         U32 rep[ZSTD_REP_NUM],
                                         void const* src,
                                         size_t srcSize) {
    return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 0);
}

size_t ZSTD_compressBlock_lazy_extDict(ZSTD_matchState_t* ms,
                                       seqStore_t* seqStore,
                                       U32 rep[ZSTD_REP_NUM],
                                       void const* src,
                                       size_t srcSize)

{
    return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 1);
}

size_t ZSTD_compressBlock_lazy2_extDict(ZSTD_matchState_t* ms,
                                        seqStore_t* seqStore,
                                        U32 rep[ZSTD_REP_NUM],
                                        void const* src,
                                        size_t srcSize)

{
    return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_hashChain, 2);
}

size_t ZSTD_compressBlock_btlazy2_extDict(ZSTD_matchState_t* ms,
                                          seqStore_t* seqStore,
                                          U32 rep[ZSTD_REP_NUM],
                                          void const* src,
                                          size_t srcSize)

{
    return ZSTD_compressBlock_lazy_extDict_generic(ms, seqStore, rep, src, srcSize, search_binaryTree, 2);
}
